Imaging Studies Research Articles

Comparative study of a rabbit model of spinal tuberculosis using different concentrations of Mycobacterium tuberculosis

BACKGROUND Tuberculosis is among the most devastating infectious diseases worldwide. Spinal tuberculosis is not easy to detect at an early stage, which without effective treatment often leads to spinal deformity and spinal cord damage which in turn cause complications such as paraplegia and quadriplegia. In this study, we established a model using three concentrations of bacteria and carried out a comprehensive evaluation of the model by imaging, general observations, and histopathological and bacteriological studies. AIM To establish a rabbit model of spinal tuberculosis and examine the effect on the model’s efficacy using different concentrations of Mycobacterium tuberculosis (M. tuberculosis ) inoculum. METHODS New Zealand rabbits were randomly divided into experimental, control and blank groups. The experimental and control animals were sensitized with complete Freund′s adjuvant, a hole was drilled beneath the upper endplate of the L6 vertebral body and filled with gelfoam sponge. The experimental group was divided into three subgroups (experimental 1, experimental 2, experimental 3) and infused with M. tuberculosis suspension at various concentrations. The control group was inoculated with saline and the blank group received no treatment. The 12-week post-operative survival rates were 100%, 80% and 30% in the experimental groups inoculated with concentrations of 106, 107 and 108 CFU/mL bacteria, respectively. RESULTS The survival rate of the control and blank groups was 100%. Vertebral body destruction at 8 weeks in the three experimental groups as determined by X-ray analysis was 33.3%, 62.5% and 66.7%, and by computed tomography (CT) and 3-dimensional CT 44.4%, 75% and 100%, respectively. At 12 weeks, the figures were 44.4%, 75% and 100% by X-ray analysis and 44.4%, 100% and 100% by CT and 3-dimensional CT, respectively. All surviving rabbits of the experimental groups had vertebral destruction. The positive bacterial culture rates were 22.2%, 75% and 66.7%, respectively, in the experimental groups. After being sensitized with complete Freund's adjuvant, large differences were observed in the extent of spinal tuberculosis after inoculation of the rabbits with different concentrations of H37RV standard M. tuberculosis . CONCLUSION The experimental 1 had a low success rate at establishing an infection. The experimental 3 resulted in high mortality and complication rates. The experimental 2 was optimum for establishing a spinal tuberculosis model based on the high level of symptoms observed and the low rabbit mortality.

Magnetic beads as intravesical foreign bodies in children: our clinical experience

PurposeTo analyze the clinical data of five patients involving intravesical magnetic beads, summarizing diagnostic and therapeutic experiences.MethodsFrom January 2018 to November 2023, five pediatric patients were treated for intravesical magnetic beads at Shenzhen Children's Hospital. We retrospectively reviewed and analyzed the records of these patients, including demographic characteristics, clinical symptoms, imaging studies, and treatment methods.ResultsAll intravesical magnetic beads were retrieved from patients’ bladders. The patients ranged from 12 to 14 years, with a mean age of 13 years. None of them had a history of psychiatric disorders. Depending on the number of magnetic beads, their aggregation state, and the time since insertion, Three cases were successfully retrieved via cystoscopy, one via pneumovesicoscopy, and another via open surgery. No complications were observed during the postoperative follow-up.ConclusionMagnetic beads are a relatively rare type of intravesical foreign bodies and should be surgically removed as soon as possible. Cystoscopy is the first method for both diagnosis and treatment. When magnetic beads cannot be retrieved via cystoscopy, pneumovesicoscopy may be a viable option for the retrieval of foreign bodies. When endoscopic techniques are unsuitable or have failed, open surgery is a necessary option.

SARCOMA HEPÁTICO FUSOCELULAR ATÍPICO: UM RELATO DE CASO

Primary hepatic sarcoma is a rare malignant tumor originating from mesenchymal cells. Most individuals are asymptomatic or present with few symptoms. Imaging studies do not reveal specific findings for this type of tumor, nor is there an increase in major tumor markers or any association with viral hepatitis. The diagnosis is based on histological and immunohistochemical results. This report aims to describe the clinical and surgical context of a specific case and the approach adopted. It was conducted as a descriptive retrospective study based on a case report managed by the general surgery team in 2014 at a public hospital in Belo Horizonte. The patient was a 70-year-old female presenting with persistent diarrhea. Imaging studies identified a tumor affecting the left lobe of the liver. After multidisciplinary analysis, a trisegmental hepatectomy was performed. The patient, initially stable in the ICU, was discharged to the general ward on the fifth postoperative day and left the hospital three weeks after surgery. She remained asymptomatic with no signs of disease recurrence after nine months of follow-up. This case highlights that primary hepatic sarcoma is a rare neoplasm identified through surgical procedures and is seldom discussed in both national and international literature. The cornerstone of treatment is surgical resection, which plays a crucial role in tumor recurrence and prognosis

Altered spontaneous brain activity in children with deprivation amblyopia: a resting-state functional magnetic resonance imaging study

BackgroundTo investigate the alterations in spontaneous brain activity and the similarities and differences between monocular deprivation amblyopia and binocular deprivation amblyopia.MethodsTwenty children with binocular deprivation amblyopia, 26 children with monocular deprivation amblyopia and 20 healthy controls underwent resting-state functional magnetic resonance imaging. The evaluation of altered spontaneous brain activity was conducted using fractional amplitude of low-frequency fluctuations (fALFF). One-way analysis of variance was employed to analyze fALFF values among the three groups. Additionally, the relationship between fALFF values and best corrected visual acuity (BCVA) was analyzed via correlation analysis.ResultsCompared to healthy controls, children with binocular deprivation amblyopia presented increased fALFF values in the left medial superior frontal gyrus, left middle frontal gyrus, left anterior cingulate cortex, left postcentral gyrus and bilateral precentral gyrus, and decreased fALFF values in the right fusiform gyrus. Compared to healthy controls, children with monocular deprivation amblyopia presented increased fALFF values in the right lingual gyrus, right superior frontal gyrus, right middle frontal gyrus, left superior temporal gyrus, triangular part of the left inferior frontal gyrus and bilateral middle temporal gyrus, and decreased fALFF values in the right precuneus. Compared with monocular deprivation amblyopia, fALFF values of binocular deprivation amblyopia were decreased in the triangular part of the left inferior frontal gyrus, right lingual gyrus and right cuneus, and increased in the left precentral gyrus and left postcentral gyrus. No significant correlations were found between the fALFF values of identified regions and the BCVA of amblyopic eyes for either type of amblyopia.ConclusionsChildren with deprivation amblyopia presented alterations in spontaneous activity in multiple brain regions, and these alterations differed between monocular amblyopia and binocular amblyopia. These abnormal spontaneous activities may reflect dysfunctions and compensation related to amblyopia.

Mechanism and Treatment of the Rotator Cuff Tear

Among all the joints in the human body, the shoulder has the highest degree of motion, but its stability is relatively limited. As the population ages more rapidly, rotator cuff tear has become the most affected muscle and joint pain lesions in middle-aged and elderly patients and the prevalence rate is increasing year by year. According to imaging studies, rotator cuff injuries affect 30% of asymptomatic adults over 60 and 65% of asymptomatic adults over 70. The rotator cuff tear made pain to the patients, reduced joint range of motion and stability, joint dysfunction. So, the people more and more attach importance to rotator cuff tear. This paper summarizes in recent years about risk factors, mechanism and the treatment of rotator cuff tear, which hope to accelerate the treatment of diseases, which can made partial or complete layer tears. Due to the diversity of rotator cuff tear classification, future studies should be carried out with specific tear size or tear degree.

Correlation of intracranial and extracranial carotid atherosclerotic plaque characteristics with ischemic stroke recurrence: a high-resolution vessel wall imaging study

ObjectivesTo evaluate the ability of the plaque characteristics of extracranial carotid and intracranial arteries to predict large atherosclerotic ischemic stroke recurrence via head and neck combined high-resolution vessel wall imaging (HR-VWI).MethodsThis prospective cohort study included 169 patients with large atherosclerotic ischemic stroke who underwent head and neck combined HR-VWI from April 2022 to May 2023. The baseline clinical data and atherosclerotic plaque characteristics of the intracranial and extracranial carotid arteries were collected, and the patients were followed up for 1 year, with the endpoint event defined as recurrent ischemic stroke. Clinical and imaging data were compared between the recurrent and nonrecurrent groups. Independent risk factors associated with stroke recurrence were assessed via multivariate Cox regression analysis. The receiver operating characteristic (ROC) curves of the relevant variables were also plotted, and the area under the curve (AUC) was calculated to assess their ability to predict stroke recurrence. Kaplan–Meier survival curves were used to compare the probability of stroke recurrence.ResultsDuring the 12-month follow-up, stroke recurrence occurred in 35 of the 169 patients. Multivariate Cox regression analysis revealed that the total number of intracranial and extracranial carotid plaques (p = 0.010) and coexisting extracranial carotid plaques and intracranial significantly enhanced plaques (p = 0.047) were independent risk factors for recurrent ischemic stroke. The AUCs for predicting stroke recurrence were 0.787 and 0.710, respectively. The Kaplan–Meier survival curve revealed that the risk of stroke recurrence was significantly greater in patients whose total number of intracranial and extracranial carotid plaques was >4.5 than in patients whose total number of plaques was <4.5 (p < 0.001) and was significantly greater in patients with coexisting extracranial carotid plaques and intracranial significantly enhanced plaques than in patients without coexisting plaques (p < 0.001).ConclusionA greater total number of intracranial and extracranial carotid plaques and the coexistence of extracranial carotid plaques and intracranially significantly enhanced plaques are independent risk factors associated with recurrent ischemic stroke. Head and neck combined HR-VWI may provide new indicators for the prediction of stroke recurrence, thus helping clinicians identify high-risk patients and target therapy to reduce the recurrence of ischemic events.

Functional resting state connectivity is differentially associated with IL-6 and TNF-α in depression and in healthy controls

Inflammatory processes have been implicated in the pathophysiology of depression. In human studies, inflammation has been shown to act as a critical disease modifier, promoting susceptibility to depression and modulating specific endophenotypes of depression. However, there is scant documentation of how inflammatory processes are associated with neural activity in patients with depression. We therefore tested the hypothesis that the peripheral inflammation markers IL-6 and TNF-α correlate with neural resting state network functional connectivity in depression using functional magnetic resonance imaging (fMRI) and compared it with healthy controls. We used fMRI to investigate the functional connectivity (FC) of the resting state Default Mode Network (DMN) and Salience/Ventral Attention Network (SAL) and their association with the peripheral inflammation markers IL-6 and TNF-α in 25 patients with depression and compared it to 24 healthy subjects. Results of this imaging study revealed that both DMN and SAL resting state networks are differentially associated with distinct immunological pathways depending on whether a person has a depressive phenotype or is healthy. While the DMN FC correlated with the concentration of the cytokine IL-6 in healthy subjects, SAL FC’s connectivity correlated with the cytokine TNF-α's concentration. This study highlights the importance of peripheral inflammatory processes in depression and suggests a modulatory effect on neural resting state networks depending on the state of depression.

Diagnosis and treatment of pediatric arterial stenosis associated with neurofibromatosis type 1

BackgroundNeurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder affecting multiple systems. However, arterial stenosis is a rare manifestation in patients with NF1. Since the symptoms of arterial stenosis caused by NF1 are often atypical and have a high under-diagnosis rate, this can lead to serious complications such as hypertension, ischemic stroke, or even death. The aim of our research is to analyse the clinical characteristics of arterial stenosis in pediatric patients with NF1 and to summarise its diagnosis, treatment and prognosis.MethodsWe conducted a retrospective review of data from patients with NF1 treated at Beijing Children’s Hospital from 2016 to 2020. Patients diagnosed with arterial stenosis, identified through clinical symptoms, physical examination, arterial ultrasonography, or imaging studies, were included in this study. These patients received symptomatic drug and/or surgical treatments and were followed up regularly. We summarized demographic characteristics, sites of arterial stenosis, clinical manifestations, and treatment outcomes.ResultAmong the 258 patients with NF1 treated at our hospital, 12 (4.7%) had arterial stenosis, comprising 9 males and 3 females with a median age of 7 years (range: 1–14 years). Renal artery stenosis was diagnosed in 7 patients (58.3%), while internal carotid artery (ICA) stenosis was diagnosed in 5 patients (41.7%). The predominant symptoms of renal artery and ICA stenosis were renal hypertension and convulsions, respectively. Antihypertensive drugs were effective in 5 patients with renal hypertension; 2 patients required balloon dilatation of the renal artery due to inadequate response to medication. Oral antiepileptic treatment was effective in 3 patients with ICA stenosis, and encephaloduroarteriosynangiosis was effective in the remaining 2 cases. The follow-up period ranged from 2 to 6 years, with a median duration of 3 years. No deterioration or mortality was observed during the follow-up period.ConclusionsArterial stenosis was present in approximately 4.7% of patients with NF1, predominantly affecting the renal artery and ICA. Renal hypertension and convulsions were the primary symptoms of renal artery and ICA stenosis, respectively. Early diagnosis and intervention can substantially improve the prognosis of these patients.

Methionine-Derived Fluorescent Probes Targeting Mitochondria: A Tool for Real-Time Oxidative Stress Monitoring in Live Cells.

Reactive oxygen species (ROS) play crucial roles in both cell signaling and defense mechanisms. Hypochlorous acid (HOCl), a strong oxidant, aids the immune response by damaging pathogens. In this study, we developed two pyridinium-based fluorophores PSSM and PSSE for selective hypochlorite detection. Out of these two fluorescent probes, PSSM shows a strong turn-on emission via a photoinduced electron transfer (PeT) mechanism, excellent mitochondrial localization, and rapid response to HOCl with high selectivity among reactive oxygen species by achieving a detection limit of 2.41 μM. It successfully detects both exogenous and endogenous HOCl in live cells, enabling the study of HOCl's role at the organelle level. Structural analysis of PSSM via thioether oxidation confirmed by HPLC, NMR and HRMS further supports its specificity. Confocal imaging and flow cytometry studies further highlights its utility in investigating oxidative stress, positioning this fluorophore as a valuable tool for monitoring HOCl imbalances in biological systems.

Differentiating Liver Metastases from Primary Liver Cancer: A Retrospective Study of Imaging and Pathological Features in Patients with Histopathological Confirmation

Background and Objectives: This study aimed to identify and analyze imaging and pathological features that differentiate liver metastases from primary liver cancer in patients with histopathological confirmation, and to evaluate the diagnostic accuracy of imaging modalities. Materials and Methods: This retrospective study included 137 patients who underwent liver biopsy or resection between 2016 and 2024, comprising 126 patients with liver metastases and 11 patients with primary liver cancer (hepatocellular carcinoma). Imaging features on contrast-enhanced MRI were evaluated, including lesion number, size, margins, enhancement patterns, presence of capsule, T1/T2 signal characteristics, diffusion-weighted imaging (DWI) signal, and portal vein thrombosis. Laboratory data such as liver function tests and alpha-fetoprotein (AFP) levels were collected. Pathological features recorded included tumor differentiation, vascular invasion, necrosis, and fibrosis. Statistical analyses were performed using chi-squared tests, t-tests, and logistic regression, with a significance level of p < 0.05. The diagnostic accuracy of imaging features was assessed using receiver operating characteristic (ROC) curve analysis. Results: Liver metastases were more likely to present as multiple lesions (82.5% vs. 27.3%, p < 0.001), had irregular margins (78.6% vs. 36.4%, p = 0.002), rim enhancement (74.6% vs. 18.2%, p < 0.001), and were hypointense on T1-weighted images (85.7% vs. 45.5%, p = 0.004). Primary liver cancers were more likely to be solitary (72.7% vs. 17.5%, p < 0.001), have smooth margins (63.6% vs. 21.4%, p = 0.002), exhibit arterial phase hyperenhancement (81.8% vs. 23.8%, p < 0.001), and portal venous washout (72.7% vs. 19.0%, p < 0.001). Vascular invasion was more common in primary liver cancer (45.5% vs. 11.1%, p = 0.01). AFP levels > 400 ng/mL were significantly associated with primary liver cancer (63.6% vs. 4.8%, p < 0.001). ROC curve analysis showed that a combination of imaging features had an area under the curve (AUC) of 0.91 for differentiating the two entities. Conclusions: Imaging features such as lesion number, margin characteristics, enhancement patterns, T1/T2 signal characteristics, and portal venous washout, along with pathological features like vascular invasion and AFP levels, can effectively differentiate liver metastases from primary liver cancer. The diagnostic accuracy of imaging is high when multiple features are combined.

Association between clinical and MRI-detected imaging findings for people with midfoot pain, a cross-sectional study.

Midfoot pain is common but poorly understood, with radiographs often indicating no anomalies. This study aimed to describe bone, joint and soft tissue changes and to explore associations between MRI-detected abnormalities and clinical symptoms (pain and disability) in a group of adults with midfoot pain, but who were radiographically negative for osteoarthritis. Community-based participants with midfoot pain underwent an MRI scan of one foot and scored semi-quantitatively using the Foot OsteoArthritis MRI Score (FOAMRIS). Foot pain and disability were recorded using visual analog scales (VAS) and the Modified-Manchester Foot Pain Disability Index (MMFPDI). Associations were assessed for continuous data using Spearman's Rho, and for categorical data, a Wilcoxon signed rank test. Linear regression was used to explore the association between participant-reported measures and MRI abnormalities, adjusted for age, sex and BMI. Sixty-one participants (70% female, mean age 48.5years, median BMI 28.6kg/m2) were included. Median VAS pain was 31/100mm (IQR 21-47) and median disability was 30/48 (IQR 26-36). There was a moderate association between midfoot pain severity and the number of joints exhibiting joint space narrowing; adjusted results suggested 31% (95% confidence interval 3%-68%) worse VAS pain with each additional affected joint. Greater numbers of joints with cysts were associated with worse VAS pain [14% (0%-31%)] and disability [1.1 units (0-2.2)]. Effusion/synovitis was associated with MMFPDI pain. No other MRI abnormalities were associated with sex, body mass and foot pain/disability measures. Bone marrow lesions, joint space narrowing, cysts and osteophytes occurred more frequently with age. MRI abnormalities were common, particularly in the talo-navicular joint, first and second cuneo-metatarsal joints. Those with dorsal foot pain had more multi-joint involvement, bone marrow lesions, joint space narrowing and cysts and for those with pain on midfoot movement, bone marrow lesions and cysts were reported. In people with midfoot pain, MRI-detected features of osteoarthritis and soft-tissue abnormalities were found, clustered in the medial and intermediate cuneiform joints. These features were more common with age but not associated with pain or disability measures. Younger people with dorsal midfoot pain exhibited early signs of bone and joint features of osteoarthritis and we recommend further imaging studies to determine the clinical and diagnostic significance.

Primary malignant melanoma of the vagina: A case report of a rare disease that is difficult to diagnose.

Malignant melanoma is a rare cancer that accounts for approximately 1% of all cancers. Primary malignant melanoma of the female genital tract accounts for approximately 3% to 7% of all malignant melanomas, and 0.3% to 0.8% of all melanomas in women. It affects postmenopausal women ages 60 to 80 years. Various hormonal factors, including puberty, pregnancy, menopause, oral contraceptive use, and human papillomavirus infection are associated with primary malignant melanoma of the vagina. Symptoms often include vaginal bleeding, discharge, and pain; however, it can also present as pigmented or nonpigmented lesions, making diagnosis challenging. Diagnosis involves detailed history, physical examination, and imaging (CT, MRI, and positron emission tomography). Immunohistochemical staining for markers, such as human melanoma black-45 and Melan-A, is crucial for confirmation. The diagnosis was made through careful physical examination, imaging studies, and immunohistochemistry. The treatment includes wide local excision, radical surgery, radiotherapy, chemotherapy, and immunotherapy. The prognosis of primary malignant melanoma of the vagina is usually poor owing to late diagnosis, and the 5-year survival rate is 5% to 25%. To consider the possibility of primary malignant melanoma of vagina, postmenopausal women, particularly those who with human papillomavirus infection, should be performed thorough examination regardless of symptoms of vaginal bleeding or discharge.

Thromboembolic Complications After Treatment with the INCRAFT AAA Ultra-Low-Profile Stent Graft System.

Low-profile endografts have reported increased rates of limb graft occlusions. The INCRAFT stent graft system is an ultra-low profile endograft for the exclusion of infrarenal abdominal aortic aneurysms. Our aim was to report thromboembolic events (TE) in patients treated with the INCRAFT device and its association with risk factors. A retrospective study was performed of 80 patients treated with the INCRAFT endograft between February 2015 and December 2022 at a single institution. All available imaging studies were reviewed by two reviewers independently. TE included intraprosthetic thrombus (IPT), limb graft occlusion (LGO) and distal embolization. A regression analysis was performed to evaluate possible risk factors associated with the development of TE. These included tortuous access vessels, IPT, access vessel diameter and the ratio between the cross-sectional area of the mainbody to the bilateral limb grafts. Limb occlusions occurred in 7 patients (9%) and 12 limbs (7.5%) resulting in a primary and secondary patency at one, three and five years of 96% and 99%, 94% and 97% and 89% and 93%, respectively. IPT was found in 36% of patients and affected endograft limbs in 93%. Ten distal occlusions in 8 patients (10.0%) were considered to origin from IPT, which led to symptomatic occlusions of below-the-knee vessels in all patients. Freedom from IPT at one, three and five years was 80%, 61%, and 43%, respectively. Age ≤70 years and access vessel diameter ≥10 mm were associated with IPT development. IPT was significantly associated with LGO (OR 77.10, p=0.003). Thromboembolic events are frequent after treatment with the INCRAFT endograft with a limb graft occlusion rate of 9% per patient and IPT found in 36% of patients. IPT was more common in patients ≤70 years and was a significant risk factor for LGO.

Coronary atherosclerosis in athletes: emerging concepts and preventive strategies.

There should be no assumption that an athlete is immune to coronary artery disease (CAD), even when traditional cardiovascular (CV) risk factors appear well-managed. Excelling in certain aspects of health does not equate to total CV protection. Recent data from cardiac imaging studies have raised the possibility that long-term, high-volume, high-intensity endurance exercise is associated with coronary atherosclerosis. Whilst the risk of CV events has not been shown to rise with athletic activity, the potential for CAD should not be overlooked as it is the leading cause of sudden cardiac death in athletes >35 years of age (i.e. 'Masters athletes'). Evaluating both traditional and non-traditional risk factors for CAD is the most important part of pre-participation evaluation in Masters athletes. When managing athletes at risk of CAD it is important to adopt a shared decision-making approach regarding lifestyle adaptation and lipid-lowering treatments. In the great majority of athletes, after excluding the presence of symptoms and inducible ischaemia, this advice should include encouragement to continue exercising as available data indicate that higher levels of fitness are associated with a markedly attenuated incidence of coronary events regardless of the severity of coronary disease. Future research is needed to establish the relationship between clinically relevant CAD outcomes and coronary artery calcification in Masters Athletes, the role of sex, as well as exploration of the mechanisms underpinning these unexpected CV adaptations.

Systematic application of saliency maps to explain the decisions of convolutional neural networks for glaucoma diagnosis based on disc and cup geometry.

This paper systematically evaluates saliency methods as explainability tools for convolutional neural networks trained to diagnose glaucoma using simplified eye fundus images that contain only disc and cup outlines. These simplified images, a methodological novelty, were used to relate features highlighted in the saliency maps to the geometrical clues that experts consider in glaucoma diagnosis. Despite their simplicity, these images retained sufficient information for accurate classification, with balanced accuracies ranging from 0.8331 to 0.8890, compared to 0.8090 to 0.9203 for networks trained on the original images.&#xD;&#xD;The study used a dataset of 606 images, along with RIM-ONE DL and REFUGE datasets, and explored nine saliency methods. A discretization algorithm was applied to reduce noise and compute normalized attribution values for standard eye fundus sectors. Consistent with other medical imaging studies, significant variability was found in the attribution maps, influenced by the method, model, or architecture, and often deviating from typical sectors experts examine. However, globally, the results were relatively stable, with a strong correlation of 0.9289 (p < 0.001) between relevant sectors in our dataset and RIM-ONE DL, and 0.7806 (p < 0.001) for REFUGE.&#xD;&#xD;The findings suggest caution when using saliency methods in critical fields like medicine. These methods may be more suitable for broad image relevance interpretation rather than assessing individual cases, where results are highly sensitive to methodological choices. Moreover, the regions identified by the networks do not consistently align with established medical criteria for disease severity.

The correlation between intracranial atherosclerosis and white matter hyperintensities in cerebral small vessel disease: a high-resolution magnetic resonance imaging study

The correlation between intracranial atherosclerosis and white matter hyperintensities in cerebral small vessel disease: a high-resolution magnetic resonance imaging study

Cortical encoding of spatial structure and semantic content in 3D natural scenes.

Our visual system enables us to effortlessly navigate and recognize real-world visual environments. Functional magnetic resonance imaging (fMRI) studies suggest a network of scene-responsive cortical visual areas, but much less is known about the temporal order in which different scene properties are analysed by the human visual system. In this study, we selected a set of 36 full-colour natural scenes that varied in spatial structure and semantic content that our male and female human participants viewed both in 2D and 3D while we recorded magnetoencephalography (MEG) data. MEG enables tracking of cortical activity in humans at millisecond timescale. We compared the representational geometry in the MEG responses with predictions based on the scene stimuli using the representational similarity analysis framework. The representational structure first reflected the spatial structure in the scenes in time-window 90-125 ms, followed by the semantic content in time-window 140-175 ms after stimulus onset. The 3D stereoscopic viewing of the scenes affected the responses relatively late, from around 140 ms from stimulus onset. Taken together, our results indicate that the human visual system rapidly encodes a scene's spatial structure and suggest that this information is based on monocular instead of binocular depth cues.Significance statement Our visual system enables us to recognize and navigate our visual surroundings seemingly effortlessly, but what exactly happens in our brains remains poorly understood. With the help of time-resolved brain imaging (magnetoencephalography, MEG), we found that the brain first encodes the spatial structure of a scene (e.g., cluttered or navigable) before its semantic content (e.g., a car park or farm). Brain imaging studies typically use 2D pictures as stimuli. Here we asked whether binocular disparity, a depth cue which arises from our two eyes seeing the scene from slightly different angles, aids the coding of the spatial structure. Our results suggest that this 3D depth cue plays little role in the rapid, initial sensing of our spatial surroundings.

The Effect of the Size of Gold Nanoparticle Contrast Agents on CT Imaging of the Gastrointestinal Tract and Inflammatory Bowel Disease.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD). CT imaging with contrast agents is commonly used for visualizing the gastrointestinal (GI) tract in UC patients. Contrast agents that provide enhanced imaging performance are highly valuable in this field. Recent studies have made significant progress in developing better contrast agents for imaging the gastrointestinal tract using nanoparticles. However, the impact of nanoparticle size on this application remains unexplored. Gold nanoparticles (AuNPs) serve as an ideal model to investigate the effect of nanoparticle size on imaging of the gastrointestinal tract due to their controllable synthesis across a broad size range. In this study, we synthesized AuNPs with core sizes ranging from 5 to 75 nm to examine the effect of the size in this setting. AuNPs were coated with poly(ethylene glycol) (PEG) to enhance stability and biocompatibility. In vitro tests show that gold nanoparticles are cytocompatible with macrophage cells (∼100% cell viability) and remain stable under acidic conditions, with no significant size changes over time. Phantom imaging studies using a clinical CT scanner indicated that there was no effect of nanoparticle size on CT contrast production, as previously demonstrated. In vivo imaging using a mouse model of acute colitis revealed a strong contrast generation throughout the GI tract for all agents tested. For the most part, in vivo contrast was independent of AuNP size, although AuNP outperformed iopamidol (a clinically approved control agent). In addition, differences in attenuation trends were observed between healthy and colitis mice. We also observed almost complete clearance at 24 h of all formulations tested (less than 0.7% ID/g was retained), supporting their value as a model platform for studying nanoparticle behavior in imaging. In conclusion, this study highlights the potential of nanoparticles as effective contrast agents for CT imaging of the gastrointestinal tract (GIT) in the UC. Further systemic research is needed to explore contrast agents that can specifically image disease processes in this disease setting.

The Neural Correlates of Physical Exercise-Induced General Cognitive Gains: A Systematic Review and Meta-Analysis of Functional Magnetic Resonance Imaging Studies.

The general-domain effect of physical exercise-induced cognitive gains in behavioral outcomes is well-documented, but a consensus on the neural correlates remains elusive. This meta-analysis aims to identify the neural correlates of physical exercise-induced general cognitive gains by examining task-related brain activation consistently modulated by physical exercise and its relationship to those gains. Our analysis of 52 studies with 1,503 participants shows that physical exercise enhances task performance (Hedges' g = 0.271) and consistently increases task-related brain activation primarily in the bilateral precuneus. These increases in task-related brain activation correlate positively with task performance improvements. Notably, physical exercise intensity, adherence, and social environment significantly modulate task-related brain activation changes induced by physical exercise. This meta-analysis offers an unprecedented comprehensive assessment of how physical exercise modulates task-related brain activation changes, providing neural evidence to support the general-domain effects on cognitive function induced by physical exercise.

Reversible Perfusion Changes during Acute Attacks in Glucose Transporter Type 1 Deficiency Syndrome: A Pediatric Case Series.

Glucose transporter type 1 deficiency syndrome (GLUT1-DS) is an uncommon condition represented by an infantile-onset disorder, frequently arising from heterozygous mutations in the SLC2A1 gene. Individuals with GLUT1-DS may present with early-onset seizures (typically manifesting before 4 years of age), developmental delay, and complex movement disorders. In fewer cases, stroke-like events or hemiplegic migraine-like symptoms are also reported, defined by unilateral paresis affecting 1 side of the body and/or one-half of the face, occasionally accompanied by speech impairment. Currently, the pathomechanism underlying these acute transient clinical manifestations is poorly understood. MR imaging studies performed in the absence of acute manifestations frequently reveal nonspecific imaging signs associated with this syndrome. We present findings obtained using the arterial spin-labeling technique for perfusion imaging and MRA during the acute onset of stroke-like episodes in a series of 4 pediatric patients with GLUT1-DS. We observed reversible hypoperfusion in the left hemisphere and associated reversible attenuation of distal MCA branches on MRA. A notable association between unilateral cerebral hypoperfusion and transient crossed cerebellar diaschisis was evident on perfusion maps as well.